Orthodontic treatment utilizes the remodeling of the alveolar bone in response to externally applied orthodontic force to a tooth. The rate of bone resorption is, therefore, one of the essential factors for understanding tooth movement during orthodontic treatment. There is the basic concept of differential force in orthodontics that an optimal force moves the canine without the movement of the molar, which is used for an anchor of the canine retraction. In this paper, the resorption rates of the alveolar bone around the molar and the canine were estimated from the clinical measurements of tooth movement and the stress analyses of tooth roots using a 3-D finite element model. The model consisted of an orthodontic spring, the canine, the second premolar, and the first and second molars. The bone resorption rate to unit stress at the molar was found to be about 0.5μm/(kPa·day) and almost the same as that of the canine. This result suggests that the concept of differential force can be described only by the difference in geometry of the roots of moved and fixed teeth.